It is known that, in fuel supply systems for internal combustion engines, the fuel is pumped out of the fuel tank to the injection valves with the aid of an electric fuel pump, the excess fuel being returned to the fuel tank via a return line.
Since a greater or smaller quantity of fuel is required in the case of different loading of the internal combustion engine, the fuel supply is regulated by the control unit of the internal combustion engine. For this purpose, the fuel pressure is, as described, for example, in German Patent Application No. 28 08 731, detected with the aid of a pressure sensor and the rotational speed and hence the delivery rate of the electric fuel pump regulated as a function of the fuel pressure measured. On the basis of the fuel pressure detected, the quantity of fuel delivered is determined, and this variable too is evaluated in the regulation of the pump.
Starting from a known fuel supply system of this kind for an internal combustion engine, an object of the present invention is to further improve the regulation of the fuel pressure and quantity of fuel delivered in the injection system by continuously observing the motor operating points.